A schnorr-like lightweight identity-based signature scheme

Abstract

The use of concatenated Schnorr signatures [Sch91] for the hierarchical delegation of public keys is a well-known technique. In this paper we carry out a thorough analysis of the identity-based signature scheme that this technique yields. The resulting scheme is of interest since it is intuitive, simple and does not require pairings. We prove that the scheme is secure against existential forgery on adaptive chosen message and adaptive identity attacks using a variant of the Forking Lemma [PS00]. The security is proven in the Random Oracle Model under the discrete logarithm assumption. Next, we provide an estimation of its performance, including a comparison with the state of the art on identity-based signatures. We draw the conclusion that the Schnorr-like identity-based signature scheme is arguably the most efficient such scheme known to date. © 2009 Springer Berlin Heidelberg.